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Biology 101 Labs: COVID Testing Lab

1st: Background

Start by reading:

So two major types of testing for COVID19 are being used right now: PCR and antibody testing.  Let’s look into each of these in detail.

2nd: Antibody Testing

ANTIBODY TESTING

Watch (how the immune system works):

Read:

protein model

3rd: PCR Testing

This is an example of a commercially available test for the normal Flu but COVID-19 testing would be similar except reverse transcriptase PCR would be used since coronaviruses are ssRNA viruses.  

Watch for PCR background.

polymerase chain reaction

Click to Expand

Step 1. Separation: The container of DNA will be heated into a ner boiling point to about 90 degrees Celsius using polymerase enzymes from a bacterium that is able to endure under high temperatures allowing the double structure of DNA to denature into two individual strands.

Step 2. Anneal: Once the temperature has decreased to about 55 degrees Celsius, two primers which are short segments of DNA that start the growth of the second strand will attach to the opposite ends of the two separated strands, annealing (binding) to their complementary base sequences in the DNA.

Step 3. Copy: On a small scale the temperature is again increased to about 72 degrees Celsius allowing the DNA polymerase, which are enzymes that build the DNA molecules to extend the primers because of it's construction of new nucleotides. The added nucleotides, while following the rules of complementary base pairing, attach to the original strands of DNA continuously until a whole new segment has been copied, ending the cycle of PCR.

polymerase chain reaction

Click to Expand

From 1 to a billion

Scientists use PCR to be able to study DNA segments by turning one DNA strands into multiple amounts. After one PCR cycle the amount of copies doubles from 1 DNA segment to 2 to 4 to 8 to 16 to 32 and so on. Once 30 cycles have occurred at least one billion DNA copies have been made in just under a few hours, further giving reason to the 'chain reaction' in it's name. 

DNA replication in cells need certain enzymes for polymerases to work, such as the helicase which unwinds the double helix. Kary Mullis, creator of the PCR technique, used in heat substitution to the helicase to separate the DNA strand. He also used polymerase enzymes from a bacterium that lives and thrives under high temperatures to prevent the DNA polymerases to break down when exposed to heat as the strand is being separated.

4th: COVID Lab Questions to Turn In

Questions to turn in:

  1. What are the two major types of testing currently being used to test for COVID19?
  2. List some advantages and drawbacks to using each test.
  3. What are effector and memory cells?  Relate their role in the humoral response to antibody testing.
  4. Using the picture of COVID19 and the Prosci article, what are some antibody targets we can use?
  5. Outline the basic steps of PCR.
  6. Based on the ID NOW video, explain how PCR can be used to detect viral infection.
  7. How does the antibody test relate to the creation of a vaccine?
  8. What is ssRNA?

Link to the questions.